The Godfrey Thomson Unit takes its names from Sir Godfrey H. Thomson (1881-1955), who served as both Professor of Education at the University of Edinburgh and Director of Studies at Moray House Training College between 1925-1951. The Unit is best known for production of the Moray House Tests, assessment tests administered to students throughout the UK, largely in England. Moray House Tests were also used in the Scottish Mental Surveys of 1932 and 1937.

Godfrey Thomson began his involvement in intelligence assessment while Chair of Education at Armstrong College, Newcastle, when he was asked by the Northumberland Authority to develop the first British group intelligence tests for use in the Special Place examination. Devised by Thomson in 1921, the Northumberland Mental Tests were administered to a large number of eleven year old children who were candidates for free places in secondary schools, and are the precursor to the Moray House Tests.

In 1925 Thomson was appointed as both Professor of Education at the University of Edinburgh and Director of Studies at Moray House Training College, stating that he would see his university and college duties merge without 'an over-nice discrimination between the two halves'. Thomson continued his studies in statistics and psychometrics in Edinburgh, and soon established a test construction and research unit. Staffed by members of the of the University of Edinburgh Education Department, the unit was located in Room 70 in the Moray House College building now known as Paterson's Land. Thus, the unit came to be known as 'Room 70' and the tests were called the Moray House Tests.

The tests primarily fall into three major categories: Verbal Reasoning (M.H.T..), English (M.H.E.) and Mathematics (M.H.M.). By 1948 Moray House Tests were administered to two out of three British children and were used and recognised throughout the world. In 1949 one and a quarter million Moray House Tests were sold, making the University the largest supplier of tests in Europe.

Royalties earned from test sales were transferred into a research fund, later registered as the Godfrey Thomson Research Fund, which was established by Thomson to support continued educational research and assessment. In particular, money was invested into improving the tests, making them as fair as possible. Established in a formal basis in 1940 when a Deed of Trust was drawn up between Thomson and the University, the Fund was later administered by trustees, with the Professor of Education as Chairman and the Principal of Moray House College of Education as Vice-Chairman. In addition to test royalties, the fund also earned income from fees paid by county Education Committees for the analysing, collating, and assessing of the results from Moray Houses Tests administered to students.

Upon Thomson's retirement in 1951, the University and College posts were once again disassociated, with John Pilley taking over Professor of Education, University of Edinburgh, while Dr. W.B Inglis became the new Director of Studies at Moray House. However, the University Department of Education, including the Room 70 research unit, continued to be accommodated at Moray House. In September 1952 the unit relocated to Room 76, although it retained the moniker Room 70. At this time the unit employed eight staff members, six of which were paid through the Thomson Research Fund. In 1965 the Room 70 unit formally became Godfrey Thomson Unit for Academic Assessment (University of Edinburgh). By the late 1960's the unit was lead by A.E.G. Pilliner and was no longer based at Moray House, instead occupying premises at Buccleuch Place, where it would remain into the 1990s.